Loading unit locking collar

ABSTRACT

A loading unit assembly includes a shell assembly and a locking collar. The shell assembly has a proximally extending annular ring that defines a cylindrical opening. The annular ring defines a lock opening that passes through the annular ring. The shell assembly defines a retention slot that is adjacent the annular ring on an opposite side of the annular ring from the lock opening. The locking collar is positioned about the annular ring and has a body, a lock, and a retention tab. The body includes a release surface. The locking collar has a locked configuration wherein the lock extends into the cylindrical opening and an unlocked configuration wherein the lock is disposed outwardly of the cylindrical opening. The side of the locking collar opposite the lock is prevented from moving outwardly in relation to the annular ring when the release surface is pressed inwardly towards the annular ring.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part and claims the benefit of,and priority to, U.S. patent application Ser. No. 14/591,193, filed Jan.7, 2015, the entire contents of which are hereby incorporated herein byreference.

BACKGROUND

1. Technical Field

The present disclosure relates generally to surgical staplinginstruments. More specifically, the present disclosure relates tocircular surgical stapling instruments including replaceable loadingunits.

2. Background of Related Art

Surgical stapling devices configured to join tissue portions during asurgical procedure are well known. These devices include linear endeffectors which are oriented parallel or transverse to a longitudinalaxis of the device as well as circular end effectors. Typically, linearstapling devices include a disposable loading unit or a replaceablecartridge that allows the stapling device to be used multiple times.However, conventional circular stapling devices include a cartridge orshell assembly that is fixedly attached to the device such that thedevice must be disposed of after a single use. Some circular staplingdevices include a cartridge or shell assembly that is replaceable.

A need exists in the art for a simple, inexpensive device for releasablysecuring a cartridge or shell assembly to a circular stapling device tofacilitate reuse of the stapling device.

SUMMARY

In an aspect of the present disclosure, a loading unit and lockingcollar assembly includes a shell assembly and a locking collar. Theshell assembly has a proximal end portion for receiving a distal endportion of a surgical instrument. The proximal end portion includes anannular ring that has an outer surface and an inner surface. The outersurface of the annular ring defines an annular groove with the proximalend portion. The annual ring defines a lock opening therethrough. Thelocking collar is releasably disposed within the annular groove andincludes an annular body. The annular body of the locking collar has apair of release surfaces and a lock. The lock extends radially inwardfrom the annular body. The pair of release surfaces is configured totransition the locking collar from a locked configuration to an unlockedconfiguration. In the locked configuration, the lock extends through thelock opening to penetrate the inner surface of the annular ring and inthe unlocked configuration the lock is positioned radially outward fromthe inner surface of the annular ring.

In aspects, each of the release surfaces is urged towards the otherrelease surface to transition the locking collar from the lockedconfiguration to the unlocked configuration. Each of the releasesurfaces may be compressed radially inward to transition the lockingcollar towards the unlocked configuration. Alternatively, each of therelease surfaces may be urged about the circumference of the lockingcollar in a plane transverse to a longitudinal axis of the shellassembly to transition the locking collar towards the unlockedconfiguration.

In some aspects, the locking collar defines an elliptical cross-sectionin a plane transverse to a longitudinal axis of the shell assembly inwhich the width in the unlocked configuration is less than the width inthe locked configuration. The width may be defined between the pair ofrelease surfaces. Alternatively, the locking collar may define anelliptical cross-section in a plane transverse to a longitudinal axis ofthe shell assembly in which the width is less than the height.

In certain aspects, the locking collar defines a circular cross-sectionin a plane transverse to a longitudinal axis of the shell assembly inthe locked configuration. The locking collar may define an ellipticalcross-section in a plane transverse to a longitudinal axis of the shellassembly in which the width is less than the height in the unlockedconfiguration. The height may be defined between the pair of releasesurfaces and the lock.

In particular aspects, the locking collar is biased towards the lockedconfiguration. The annular body of the locking collar may split to fromthe first and second release surfaces. The first release surface mayextend in a first direction about the circumference of the annular bodyand the second release surface may extend in a second direction oppositethe first direction about the circumference of the annular body. Thefirst and second release surfaces may each include an end that definesan engagement window between the end and the annular body. The lockingcollar may be configured to provide indicia when the locking collartransitions from the unlocked configuration to the locked configuration.The indicia may be audible. The shell assembly may be configured to firestaples through tissue.

In another aspect of the present disclosure, a surgical system includesa surgical instrument, a loading unit, and a locking collar. Thesurgical instrument includes a distal end. A loading unit includes ashell assembly that has a proximal end portion positioned over thedistal end of the surgical instrument. The proximal end portion includesan annular ring that has an outer surface and an inner surface. Theouter surface of the annular ring defines an annular groove with theproximal end portion. The annular ring defines a lock openingtherethrough. The locking collar is releasably disposed within theannular groove of the loading unit and includes an annular body that hasa pair of release surfaces and a lock. The lock extends radially inwardfrom the annular body. The pair of release surfaces is configured totransition the locking collar from a locked configuration to an unlockedconfiguration. In the locked configuration the lock extends through thelock opening to penetrate the inner surface of the annular ring and inthe unlocked configuration the lock is positioned radially outward fromthe inner surface of the annular ring.

In aspects, the distal end of the surgical instrument defines a window.The lock may extend into the window in the locked configuration and maybe positioned outside the window in the unlocked configuration. Thelocking collar may secure the loading unit to the distal end of thesurgical instrument in the locked configuration and the locking collarmay allow the loading unit to be removed from the surgical instrument inthe unlocked configuration. The lock may include a proximal step, adistal step, and an angled surface between the proximal and distalsteps. The angled surface may be configured to slide over the distal endportion of the surgical instrument to move the lock radially outwarduntil the lock is positioned within windows defined in the distal end ofthe surgical instrument.

In another aspect of the present disclosure, a loading unit and lockingcollar assembly includes a shell assembly and a locking collar. Theshell assembly has a proximally extending annular ring that defines acylindrical opening. The annular ring defines a lock opening that passesthrough the annular ring. The shell assembly defines a first retentionslot that is adjacent the annular ring on an opposite side of theannular ring from the lock opening. The locking collar is positionedabout the annular ring. The locking collar has a body, a lock, and afirst retention tab. The body includes at least one release surface. Thelock extends from an inner surface of the body spaced from the at leastone release surface. The locking collar has a locked configuration andan unlocked configuration. In the locked configuration, the lock extendsthrough the lock opening into the cylindrical opening. In the unlockedconfiguration, the lock is disposed outwardly of the cylindricalopening. The first retention tab is received within the first retentionslot to prevent a side of the locking collar opposite the lock frommoving outwardly in relation to the annular ring when the at least onerelease surface is pressed inwardly towards the annular ring.

In aspects, the at least one release surface includes two releasesurfaces positioned on opposite sides of the body. The two releasesurfaces may be moveable inwardly towards one another to transition thelocking collar to the unlocked configuration. The annular ring maydefine a relief groove adjacent each of the two release surfaces. Therelease grooves may allow inward movement of the body of the lockingcollar in the area of the release surfaces. The body may be resilientand the resilience of the body may urge the locking collar towards thelocked configuration.

In some aspects, the assembly includes a retention ring that ispositioned about the annular ring proximal of the locking collar. Theretention ring may define a second retention slot. The locking collarmay include a second retention tab that is received within the secondretention slot to prevent the side of the locking collar opposite thelock from moving outwardly when the at least one release surface ispressed inwardly towards the annular ring. The first and secondretention tabs may be axially aligned with one another.

In particular aspects, the annular ring defines a retention groove thatextends in a direction parallel to a longitudinal axis of the shellassembly. The first and second retention tabs extend from opposite sidesof a retention rib that extends inwardly from an inner surface of thebody. The retention rib may be disposed in the retention groove. Theshell assembly may include a cover that extends distally over theretention groove to define the first retention slot. The body of thelocking collar may define a cutout positioned adjacent the firstretention tab. The cutout may be sized to receive the cover of the shellassembly.

In certain aspects, the annular ring defines retention openings thatpass through the annular ring. The retention ring may include lockingtabs that extend from an inner surface of the retention ring which areeach received in a respective one of the retention openings to fix theretention ring to the annular ring. The retention openings may beunequally spaced about the annular ring. The locking tabs may define awedge shape with an angled surface of the wedge facing distally. Aproximal end of the annular ring may define chamfers that are eachaxially aligned with each of the retention openings and/or the lockopening.

In another aspect of the present disclosure, a surgical system includesa surgical instrument, a shell assembly, and a locking collar. Thesurgical instrument includes a distal end that defines a lock windowthrough the distal end. The shell assembly has a proximally extendingannular ring that defines a cylindrical opening. The annular ringdefines a lock opening that passes through the annular ring. The shellassembly defines a first retention slot adjacent the annular ring on anopposite side of the annular ring from the lock opening. The distal endof the surgical instrument is received within the cylindrical openingwith the lock opening radially aligned with the lock window. The lockingcollar is positioned about the annular ring. The locking collar has abody, a lock, and a first retention tab. The body includes a releasesurface. The lock extends from an inner surface of the body spaced apartfrom the release surface. The locking collar has a locked configurationand an unlocked configuration. In the locked configuration, the lockextends into the lock windows to secure the shell assembly to the distalend of the surgical instrument. In the unlocked configuration, the lockis disengaged from the lock window such that the shell assembly isdetachable from the distal end of the surgical instrument. The firstretention tab is received within the first retention slot to prevent aside of the locking collar opposite the lock from moving outwardly inrelation to the annular ring when the release surface is pressedinwardly towards the annular ring.

In another aspect of the present disclosure, a method of using a loadingunit includes aligning a locking collar with a shell assembly andsliding the loading unit distally over a proximally extending annularring of the shell assembly. A lock of the locking collar engages theannular ring such that the lock is moved outwardly towards an unlockedconfiguration of the locking collar until the lock is aligned with alock opening defined through the annular ring. Resilience of a body ofthe lock collar urges the locking collar towards a locked configurationof the locking collar to move the lock through the lock opening. Aretention tab of the locking collar is positioned on an opposite side ofthe locking collar from the lock and slides into a retention slotdefined by the shell assembly to prevent the opposite side of thelocking collar from moving outwardly.

In aspects, the method includes attaching the loading unit to a distalend of a surgical instrument by aligning the loading unit with thedistal end of the surgical instrument and sliding the loading unit overthe distal end of the surgical instrument such that the lock of thelocking engages the distal end of the surgical instrument. The distalend may move the lock outwardly to urge the locking collar towards theunlocked configuration until the lock is aligned with a locking windowdefined in the distal end of the surgical instrument. The lock may beurged through the locking window by resilience of the body of thelocking collar to secure the loading unit to the distal end of thesurgical instrument.

In some aspects, the method includes actuating a shell assembly of theloading unit with the surgical instrument after the loading unit isattached to the distal end of the surgical instrument. The method mayinclude detaching the loading unit from the distal end of the surgicalinstrument after actuating the shell assembly by moving a releasesurface of the locking collar inwardly to move the lock outwardly andsliding the loading unit off of the distal end of the surgicalinstrument. Moving the release surface of the locking collar inwardlymay disengage the lock from the locking window of the distal end of thesurgical instrument. The retention tab of the locking collar may engagethe shell assembly to prevent the side of the locking collar oppositethe lock from moving outwardly in response to moving the release surfaceof the locking collar inwardly.

Further, to the extent consistent, any of the aspects described hereinmay be used in conjunction with any or all of the other aspectsdescribed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of the present disclosure are described hereinbelow withreference to the drawings, which are incorporated in and constitute apart of this specification, wherein:

FIG. 1A is a perspective view of a circular stapling surgical instrumentin accordance with the present disclosure with a loading unit releasablycoupled to a distal end of the surgical instrument;

FIG. 1B is a perspective view of another circular stapling adapter inaccordance with the present disclosure with the loading unit of FIG. 1Areleasably coupled to a distal end of the surgical instrument;

FIG. 2A is a perspective view of the adapter of FIG. 1A with the loadingunit decoupled from the surgical instrument;

FIG. 2B is a perspective view of the loading unit of FIG. 1A with thelocking collar separated therefrom;

FIG. 3 is an enlarged side view of the distal end of the surgicalinstrument and loading unit of FIG. 1A;

FIG. 4 is a side cross-sectional view taken along the longitudinal axisof FIG. 3;

FIG. 5 is an enlarged view of the indicated area of detail of FIG. 4;

FIG. 6 is a partial cross-sectional view taken along the section line6-6 of FIG. 4 illustrating showing the distal end of the surgicalinstrument and the locking collar in the locked configuration;

FIG. 7 is a partial cross-sectional view similar to FIG. 6 with thedistal end of the adapter and the locking collar in the unlockedconfiguration with a locked configuration of the locking collar shown indashed lines;

FIG. 8 is an enlarged side cross-sectional view similar to FIG. 5 withthe locking collar in the unlocked configuration;

FIG. 9 is a perspective view of another locking collar in accordancewith the present disclosure;

FIG. 10 is a front view of the locking collar of FIG. 9 in a lockedconfiguration;

FIG. 11 is a cross-sectional view taken along the section line 11-11 ofFIG. 10;

FIG. 12 is an end view of the locking collar of FIG. 9 in an unlockedconfiguration with a locked configuration of the locking collar shown indashed lines;

FIG. 13 is a perspective view of another loading unit provided inaccordance with the present disclosure;

FIGS. 14A and 14B are exploded perspective views of the loading unit ofFIG. 13;

FIG. 15 is a cross-sectional view taken along the section line 15-15 ofFIG. 13;

FIG. 16 is an enlarged view of the indicated area of detail of FIG. 15;

FIG. 17 is a cross-sectional view taken along the section line 17-17 ofFIG. 13;

FIG. 18 is a rear view of the loading unit of FIG. 13 with the lockingcollar in a locked configuration; and

FIG. 19 is a rear view of the loading unit of FIG. 13 with the lockingcollar in an unlocked configuration.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure are now described in detail withreference to the drawings in which like reference numerals designateidentical or corresponding elements in each of the several views. Asused herein, the term “clinician” refers to a doctor, a nurse, or anyother care provider and may include support personnel. Throughout thisdescription, the term “proximal” refers to the portion of the device orcomponent thereof that is closest to the clinician and the term “distal”refers to the portion of the device or component thereof that isfarthest from the clinician.

With reference to FIGS. 1A and 2A, a loading unit 10 is provided inaccordance with an embodiment of the present disclosure. The loadingunit 10 is configured for selective connection to a powered hand heldelectromechanical instrument (not shown) via an adapter 102 of asurgical instrument. Alternatively, the loading unit 10 can beconfigured for connection directly to a manually actuated handleassembly or stapling instrument 700 (FIG. 1B) such as described in U.S.Pat. No. 8,789,737 (“the '737 Patent”), which is incorporated in itsentirety herein by reference. In the embodiment illustrated in FIGS. 1Aand 2A, the loading unit 10 is releasably coupled to a distal endportion 110 of the adapter 102 and includes a staple cartridge 12 (FIG.4), a shell assembly 20, and a locking collar 40. The loading unit 10may also include an anvil 400 as shown in the illustrative embodiment ofFIG. 1B. The adapter 102 is configured to translate movement of astapling instrument, e.g., an electromechanical instrument (not shown),to actuate the staple cartridge 12 to suture and cut tissue (not shown).A proximal end 104 of the adapter 102 is attachable to the staplinginstrument to actuate the staple cartridge 12. It is contemplated thatthe proximal end 104 of the adapter 102 may be attached to a manuallyactuated instrument such as described in the '737 Patent to actuate thestaple cartridge 12.

For a detailed description of the structure and function of an exemplaryadapter and loading unit, please refer to commonly owned U.S.Provisional Patent Application Ser. No. 62/066,518, filed Oct. 21, 2014,and entitled “Adapter, Extension, and Connector Assemblies for SurgicalDevices.” For a detailed description of the structure and function of anexemplary electromechanical instrument, please refer to U.S. PatentPublication No. 2012/0253329. Each of these applications is incorporatedherein by reference in its entirety.

Referring to FIG. 2A, the distal end portion 110 of surgical instrument,e.g., the adapter 102, defines a window 112. The window 112 passesthrough the outer surface of the distal end portion 110 of the adapter102 and is spaced-apart from a distal end 110 a of the adapter 102.

Referring also to FIG. 2B, the shell assembly 20 includes a proximal endportion 22 that defines a cylindrical opening 21 (FIG. 2A) for receivingthe distal end portion 110 of the adapter 102 and a distal end 32 thatdefines a receptacle 34 for receiving and supporting the staplecartridge 12 (FIG. 4). The proximal end portion 22 of the shell assembly20 includes a recessed annular ring 23 (FIG. 2B) that defines a groove24 sized to receive the locking collar 40. In embodiments, the lockingcollar 40 has a thickness equal to the depth of the groove 24 such thatthe locking collar 40 forms a continuous or smooth surface with theouter surface of the proximal end portion 22 of the shell assembly 20.The annular ring 23 defines a lock opening 28 (FIG. 5) that receives aportion of the locking collar 40 as detailed below and defines inner andouter surfaces 23 a, 23 b.

The proximal end portion 22 of the shell assembly 20 supports a collarretainer 25 that retains the locking collar 40 within the groove 24. Thecollar retainer 25 may also be tapered to provide a smooth transitionfrom the outer diameter of the locking collar 40 to the distal endportion 110 of the adapter 102 (or alternatively, the instrument 700FIG. 1B). The collar retainer 25 may include locking features 26 (FIG.2A) which secure the collar retainer 25 to the proximal end portion 22of the shell assembly 20. It is contemplated that the collar retainer 25may be secured to the proximal end portion 22 of the shell assembly 20by any known means including, but not limited to, press-fitting orultrasonic welding tabs and interlocking structure. It is alsocontemplated that the collar retainer 25 may be integrally formed withthe proximal end portion 22 of the shell assembly 20.

With reference to FIGS. 3-6, the locking collar 40 includes a generallyannular body 42 that is sized to fit within the groove 24 of theproximal end portion 22 of the shell assembly 20 and a lock 44 thatextends radially inward from the annular body 42. The locking collar 40is positioned about the proximal end portion 22 such that the lock 44 isradially aligned with the lock opening 28. The lock 44 includes aproximal step 45, a distal step 48, and an angled surface 46 positionedbetween the proximal and distal steps 45, 48. The proximal step 45extends radially inward a first distance from the longitudinal axis A-Aof the shell assembly 20 and the distal step 48 extends radially inwarda second distance from the longitudinal axis A-A of the shell assembly20 less than the first distance. The lock 44 may also include a landing47 between the angled surface 46 and the distal step 48 that issubstantially parallel to the longitudinal axis A-A of the shellassembly 20. The distal step 48 is positioned to engage a distal walldefining the lock opening 28 of the annular ring 23 of the shellassembly 20. The proximal step 45 is positioned adjacent a proximal wallof the lock opening 28 to longitudinally fix the locking collar 40 tothe proximal end portion 22 of the shell assembly 20.

The locking collar 40 may be made of a resilient material. For example,the locking collar 12 may be formed of a resilient plastic materialusing an injection molding process. However, it is contemplated thelocking collar 40 may be formed of other suitable materials including,but not limited to, spring steel, stainless steel, or wire.

With particular reference to FIG. 6, the locking collar 40 includesfirst and second release surfaces 41 a, 41 b. Lock 44 may be positionedon the annular body 42 halfway between the first and second releasesurfaces 41 a, 41 b. In a locked configuration, the annular body 42defines a generally elliptical shape where the annular body 42 has awidth along a first axis B-B (from the first release surface 41 a to thesecond release surface 41 b) that is greater than its height along asecond axis C-C (from the lock 44 to the side opposing the lock 44). Theannular body 42 is biased towards the locked configuration such that thelock 44 when positioned about the annular ring 23 penetrates the innersurface 23 a of the annular ring 23 (FIG. 5) and extends into the window112 of the distal end portion 110 of the adapter 102 to secure theloading unit 10 to the surgical instrument, e.g., the adapter 102. Theannular body 42 is positioned within the groove 24 about the annularring 23 such that the distal step 48 (FIG. 5) engages a distal wall 112a (FIG. 5) defining the window 112 of the adapter 102 to longitudinallyfix the shell assembly 20 to the distal end portion 110 of the adapter102 of the surgical instrument. It will be appreciated that the lockopening 28 of the annular ring 23 of the shell assembly 20 is alignedwith the window 112 of the adapter 102 in the locked configuration topermit the lock 44 to pass through the lock opening 28 and the window112 as detailed above.

FIGS. 7 and 8 illustrate the locking collar 40 in an unlockedconfiguration with the annular body 42 defining a generally ellipticalshape where the height is greater than the width. The release surfaces41 a, 41 b can be manually pressed together to move the locking collar40 to the unlocked configuration. In the unlocked configuration, thelock 44 is moved radially outward by distance “D” shown in FIG. 7 suchthat the lock 44 is positioned radially outward from the inner surface23 a of the annular ring 23 (FIG. 5). The distance “D” is greater thanthe distance that the lock 44 extends into the window 112 of the adapter102 such that in the unlocked configuration, the loading unit 10 isdisengaged and removable from the distal end portion 110 of the adapter102 when the locking collar 40 is in an unlocked configuration. It iscontemplated that the distance “D” may be greater than the seconddistance that the distal step 48 of the lock 44 extends radially inwardsuch that in the unlocked configuration, the lock 44 is removed from thewindow 112 of the adapter 102 and the lock opening 28 of the proximalend portion 22 of the shell assembly 20. As shown, in the unlockedconfiguration, the height is greater than the width; however, it iscontemplated that in the unlocked configuration the width may be greaterthan the height with the lock 44 moved outward by the distance “D”.

Referring back to FIGS. 2-4, to couple the loading unit 10 to thesurgical instrument, e.g., the adapter 102, the loading unit 10 isaligned with the adapter 102 such that the distal end portion 110 of theadapter 102 is positioned within the cylindrical opening 21 of theproximal end portion 22 with the window 112 of the adapter 102 radiallyaligned with the lock opening 28 of the annular ring 23 and the lock 44of the locking collar 40. The outer surface of the locking collar 44 mayinclude visual or tactile indicia as to the location of the lock 44.With the loading unit 10 aligned with the adapter 102, the loading unit10 is moved proximally over the distal end portion 110 of the adapter102 until the lock 44 is received within the window 112 of the adapter102. It will be appreciated that the lock 44 passes through the lockopening 28 to be received within the window 112 of the adapter 102. Asthe loading unit 10 is moved proximally over the distal end 110 of theadapter 102, the angled surface 46 of the lock 44 engages the distal endportion 110 of the adapter 102 to transition, i.e., perform a cammingaction to deform, the locking collar 40, against the natural resilienceof the annular body 42, from the locked configuration towards anunlocked configuration until the window 112 moves into alignment withthe lock 44. When the window 112 moves into alignment with the lock 44,the lock 44 is snaps into the window 112. The snapping movement of thelocking collar 40 may provide visual or audible indicia that the lock 44is received within the window 112. It will be appreciated that thenatural resilience of the annular body 42 of the locking collar 40 urgesthe lock 44 through the window 112 in the adapter 102. When the lock 44is positioned within the window 112, the distal step 48 of the lockingcollar 40 engages the wall 112 a of the adapter 102 defining the window112 to longitudinally secure the shell assembly 20 of the loading unit10 to the adapter 102. In addition, when the lock 44 is received withinthe window 112, the lock 44 prevents the loading unit 10 from rotatingor twisting (i.e., radially secure) relative to the surgical instrument,e.g., the adapter 102.

With the loading unit 10 is coupled to the surgical instrument, e.g.,the adapter 102, the surgical instrument and loading unit 10 may be usedto perform a surgical procedure. After surgical procedure is completed,the loading unit 10 can be decoupled or detached from the surgicalinstrument as will be discussed in detail below. When the loading unit10 is decoupled from the surgical instrument, another loading unit maybe coupled to the surgical instrument for continued use in the surgicalprocedure, the surgical instrument may be sterilized for use in anothersurgical procedure, or the surgical instrument may be discarded. Inaddition, the loading unit 10 may be sterilized for use in anothersurgical procedure or may be discarded.

To decouple or remove the loading unit 10 from the surgical instrument,e.g., the adapter 102, the locking collar 40 is transitioned to theunlocked configuration by compressing the first and second releasesurfaces 41 a, 41 b towards one another along the first axis B-B, asrepresented by arrows “F” shown in FIG. 7. It is contemplated, that thelocking collar 40 may be transitioned to the unlocked configuration bycompressing only one of the first and second release surfaces 41 a, 41 btowards the other release surface 41 a, 41 b as shown in FIG. 7. Withthe locking collar 40 in the unlocked configuration, the shell assembly20 can be removed from engagement with the distal end portion 110 of theadapter 102 by moving the shell assembly 20 axially in relation to theadapter 102.

Referring now to FIGS. 9-12, another locking collar 140 is provided inaccordance with the present disclosure and includes a lock 44 and anannular body 142. The lock 44 of locking collar 140 is substantiallysimilar to the lock 44 of the locking collar 40 as detailed above andwill not be discussed further below except for how it relates to lockingcollar 140. The annular body 142 of the locking collar 140 is similar tothe annular body 42 of the locking collar 40 detailed above, as suchonly the differences will be detailed below for reasons of brevity.

The annular body 142 is split at one side to form first and secondrelease surfaces or end portions 144, 146 which are moveably positionedin relation to each other such that the diameter of the locking collar140 can be selectively changed, as described below. The first endportion 144 extends in a first direction about the circumference of theannular body 142 and the second end portion 146 extends in a seconddirection opposite the first direction about the circumference of theannular body 142. The first and second release surfaces 144, 146 arepositioned about the annular body 142 opposing the lock 44. Each of thefirst and second end portions 144, 146 has an end 145, 147 that definesan engagement window 149 adjacent the annular body 142. Each of thefirst and second end portions 144, 146 has a thickness along thelongitudinal axis of the loading unit 10 (FIG. 1) approximately half thethickness of the annular body 142 such that the first and second endportions 144, 146 overlap one another about the circumference of theannular body 142.

With particular reference to FIGS. 10 and 12, the locking collar 140 isformed of a resilient material having a natural resiliency to urge thelocking collar 140 towards a locked configuration (FIG. 10). In thelocked configuration, the annular body 142 defines a substantiallycircular cross-section in a plane transverse to the longitudinal axis ofthe loading unit 10 (FIG. 1). In an unlocked configuration of thelocking collar 140 (FIG. 12), the annular body 142 defines a generallyelliptical cross-section in a plane transverse to the longitudinal axisof the loading unit 10. In the unlocked configuration, the lock 44 ismoved a distance “E′” away from the first and second end portions 144,146. The locking collar 140 is transitioned towards the unlockedconfiguration by urging the ends 145, 147 of the first and second endportions 144, 146, respectively, towards one another as represented bythe arrows “F.” As the ends 145, 147 are urged towards one another, theannular body 142 moves the lock 44 the distance “E” away from the ends145, 147. The first and second end portions 144, 146 may include visualor tactile indicia in the form of arrows (FIG. 9) as to the direction tourge the first and second end portions 144, 146 to move the lockingcollar 140 towards the unlocked configuration.

With reference to FIGS. 13-19, another loading unit 210 is provided inaccordance with the present disclosure. As detailed below, the loadingunit 210 includes retention tabs 252, 254 that are received withinretention slots 238, 264 of a shell assembly 220 to prevent one side ofa locking collar 240 from moving outward of the shell assembly 220 whenrelease surfaces 241 a, 241 b of the locking collar 240 are compressedor squeezed. By limiting outward movement of one side of the lockingcollar 240, outward movement of the opposite side of the locking collar240 is amplified to reduce the extent of inward movement of the releasesurfaces 241 a, 241 b necessary to release the loading unit 210 from adistal end of an instrument as discussed in detail below. The loadingunit 210 includes the shell assembly 220, the locking collar 240, andthe retention ring 260. The shell assembly 220 is similar to the shellassembly 20 detailed above. As such, discussion of similar features willbe limited for reasons of brevity.

Referring now to FIGS. 13-14B, the shell assembly 220 includes aproximally extending annular ring 223. The annular ring 223 definesretention openings 226, a lock opening 228, relief grooves 232, and aretention groove 234. The retention openings 226 are spaced about theannular ring 223. It is contemplated that the retention openings 226 maybe equally or unequally spaced about the annular ring 223. The reliefgrooves 232 are defined about the annular ring 223 such that the reliefgrooves 232 diametrically oppose one another. The lock opening 228 maybe positioned halfway between the relief grooves 228. The relief grooves232 may be flats such that the curvature of the annular ring 223flattens to form the relief grooves 232. The retention groove 234 ispositioned between relief grooves 232 opposite the lock opening 228. Theretention groove 234 extends in a direction parallel to the longitudinalaxis of the shell assembly 220 and may be positioned halfway between therelief grooves 232. The shell assembly 220 includes a proximallyextending retention cover 238 that extends partially over the retentiongroove 234 to define a retention slot 236.

The locking collar 240 includes release surfaces 241 a, 241 b, agenerally annular body 242, a lock 244, and a retention rib 250 (FIG.14B). The release surfaces 241 a, 241 b, the body 242, and the lock 244are similar to the release surfaces 41 a, 41 b, body 42, and the lock44, respectively, detailed above with regard to locking collar 40 andwill not be described herein below for reasons of brevity. The annularbody 242 is sized to slidably receive the annular ring 223 of the shellassembly 220. The retention rib 250 extends inwardly from an innersurface of the body 242 between the release surfaces 241 a, 241 b andopposing the lock 244. The retention rib 250 includes proximal anddistal retention tabs 252, 254 extending from the body 242. Inembodiments, the distal side of the body 242 defines a retention cutout258 (FIG. 14A) that is sized to receive the retention cover 238 of theshell assembly 220. As described in greater detail below, the retentionrib 250 is received within the retention groove 234 to rotationallyalign or index the locking collar 240 with the shell assembly 220.

The retention ring 260 is positioned over the annular ring 223 of theshell assembly 220 at a position proximal to the locking collar 240 toretain the locking collar 240 over the annular ring 223 of the shellassembly 220. The retaining ring 260 includes locking tabs 262 anddefines a retaining slot 264 (FIG. 14B). The locking tabs 262 extendfrom the inner surface of the retention ring 260 and are sized to bereceived within respective retention openings 226 of the annular ring223. Each of the locking tabs 262 defines a distally facing wedge thatis configured to flex the retention ring 260 outward as the retentionring 260 is slid over the annular ring 223 until the locking tabs 262are aligned with the retention openings 226. When the locking tabs 262are aligned with the retention openings 226, the locking tabs 262 snapthrough the retention openings 226 to fix the retention ring 260 to theannular ring 223. The locking tabs 262 of the retention ring 260 and theretention openings 226 of the annular ring 223 are positioned about theannular ring 223 such that when the locking tabs 262 are received withinthe retention openings 226, the retention slot 264 is rotationallyaligned with the retention groove 234 of the annular ring 223. Theannular ring 223 may define chamfers 226 a at a distal end of theannular ring 223 to assist in rotationally aligning the retention ring260 with the annular ring 223 and to assist in sliding the retentionring 260 over the annular ring 223.

Referring also to FIGS. 15-17, a method of assembling the loading unit210 is disclosed in accordance with the present disclosure. Initiallyreferring to FIGS. 14A and 14B, the locking collar 240 is aligned withthe shell assembly 220 such that the retention rib 250 of the lockingcollar 240 is aligned with the retention groove 234 defined in theannular ring 223 of the shell assembly 220. When the locking collar 240is aligned with the shell assembly 220, the locking collar 240 is sliddistally over the annular ring 223 with the retention rib 250 slidingwithin the retention groove 234. The locking collar 240 is slid distallyover the annular ring 223 until the lock 244 of the locking collar 240is disposed within the lock opening 228 of the annular ring 223. Theannular ring 223 may define a lock chamfer 228 a (FIG. 16) axiallyaligned with the lock opening 228 to assist in rotationally aligning thelocking collar 240 with the annular ring 223 and to assist in slidingthe locking collar 240 over the annular ring 223. As the locking collar240 is slid distally over the annular ring 223, the lock 244 will abutthe annular ring 223. To facilitate placement of the locking collar 240on the annular ring 223, the release surfaces 241 a, 241 b can bepressed towards one another as the locking collar 240 is slid over theannular ring 223 to flex the body 242 of the locking collar 240 to movethe lock 244 outward beyond the annular ring 223. When the lock 244 isaligned with the lock opening 228, the release surfaces 241 a, 241 b arereleased such that the lock 244 snaps through the lock opening 288 asshown in FIG. 16.

With particular reference to FIG. 16, as the locking collar 240 is slidover the annular ring 223, the retention rib 250 is received within theretention groove 234 of the annular ring 223 until the distal retentiontab 254 is received within the retention slot 236 of the shell assembly220. With the locking collar 240 positioned about the annular ring 223,the retention ring 260 is slid distally over the annular ring 223 tosecure the locking collar 240 on the annular ring 223. In order to slidethe retention ring 260 about the annular ring 223, the retention ring260 is radially aligned with the annular ring 223 and the locking collar240 such that the retention slot 264 of the retention ring 260 isaligned with the proximal retention tab 252 of the retention rib 250 andthe retention groove 234 of the shell assembly 220. When the retentionring 260 is positioned over the annular ring 223, the locking tabs 262snap through the retention openings 226 of the annular ring 223 to fixthe retention ring 260 to a proximal end of the annular ring 223.

Referring to FIGS. 17-19, the relief grooves 232 of the annular ring 223provide clearance under the release surfaces 241 a, 241 b of the body242 of the locking collar 240 to facilitate inward movement of therelease surfaces 241 a, 241 b as detailed below. When the releasesurfaces 241 a, 241 b are pressed inwardly as shown in FIG. 19, theretention tabs 252, 254 (FIG. 16) of the locking collar 240 prevent theside of the body 242 of the locking collar 240 opposite the lock 244from moving outwardly. As such, when the release surfaces 241 a, 241 bare pressed inwardly, only the side of the locking collar 240 supportingthe lock 244 moves outwardly. By retaining or preventing the side of thebody 242 opposite the lock 244 from moving outwardly, the extent ofinward movement of the releases surfaces 241 a, 241 b required todisplace or move the lock 244 out of the lock opening 228 is reducedwhen compared to locking collar 40, detailed above.

As shown in FIG. 19, when both release surfaces 241 a, 241 b are movedinwardly, the lock 244 is moved outwardly such that the lock 244 ispositioned outside of a cylindrical opening 221 defined by the annularring 223 and beyond an outer surface of the annular ring 223. Thisallows the loading unit 210 to be detachable or slidable off a distalend of an adapter or surgical instrument as detailed above. It iscontemplated that the relief grooves 232 can be configured such that itis necessary to move only one of the release surfaces 241 a, 241 binwardly to move the lock 244 outwardly to allow detachment of theloading unit 210 from a distal end of an adapter or surgical instrumentas detailed above.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Any combination ofthe above embodiments is also envisioned and is within the scope of theappended claims. The present disclosure is not limited to circularstapling loading units, but has application to loading units for linearstapling or other types of instruments, such as electrocautery orultrasonic instruments. Therefore, the above description should not beconstrued as limiting, but merely as exemplifications of particularembodiments. Those skilled in the art will envision other modificationswithin the scope of the claims appended hereto.

What is claimed:
 1. A loading unit and locking collar assembly, theassembly comprising: a shell assembly having a proximally extendingannular ring that defines a cylindrical opening, the annular ringdefining a lock opening therethrough, the shell assembly defining afirst retention slot adjacent the annular ring on an opposite side ofthe annular ring from the lock opening; a locking collar positionedabout the annular ring, the locking collar having a body, a lock, and afirst retention tab, the body including at least one release surface,the lock extending from an inner surface of the body spaced from the atleast one release surface, the locking collar having a lockedconfiguration wherein the lock extends through the lock opening into thecylindrical opening and an unlocked configuration wherein the lock isdisposed outwardly of the cylindrical opening, the first retention tabbeing received within the first retention slot to prevent a side of thelocking collar opposite the lock from moving outwardly in relation tothe annular ring when the at least one release surface is pressedinwardly towards the annular ring.
 2. The assembly according to claim 1,wherein the at least one release surface includes two releases surfaces,the two release surfaces being positioned on opposite sides of the bodyand being moveable inwardly towards one another to transition thelocking collar to the unlocked configuration.
 3. The assembly accordingto claim 2, wherein the annular ring defines a relief groove adjacenteach of the two release surfaces, the relief grooves allowing inwardmovement of the body of the locking collar in the area of the releasesurfaces.
 4. The assembly according to claim 1, wherein the body isresilient and the resilience of the body urges the locking collartowards the locked configuration.
 5. The assembly according to claim 1,further comprising a retention ring positioned about the annular ringproximal of the locking collar, the retention ring defining a secondretention slot.
 6. The assembly according to claim 5, wherein thelocking collar includes a second retention tab received within thesecond retention slot to prevent the side of the locking collar oppositethe lock from moving outwardly when the at least one release surface ispressed inwardly towards the annular ring.
 7. The assembly according toclaim 6, wherein the first and second retention tabs are axially alignedwith one another.
 8. The assembly according to claim 6, wherein theannular ring defines a retention groove that extends in a directionparallel to a longitudinal axis of the shell assembly, and wherein thefirst and second retention tabs extend from opposite ends of a retentionrib that extends inwardly from an inner surface of the body, theretention rib being disposed in the retention groove.
 9. The assemblyaccording to claim 8, wherein the shell assembly includes a coverextending distally over the retention groove to define the firstretention slot.
 10. The assembly according to claim 9, wherein the bodyof the locking collar defines a cutout positioned adjacent the firstretention tab, the cutout being sized to receive the cover of the shellassembly.
 11. The assembly according to claim 5, wherein the annularring defines retention openings, and wherein the retention ring includeslocking tabs extending from an inner surface thereof, each of thelocking tabs being received in a respective one of the retentionopenings to fix the retention ring to the annular ring.
 12. The assemblyaccording to claim 11, wherein the retention openings are unequallyspaced about the annular ring.
 13. The assembly according to claim 11,wherein the locking tabs define a wedge shape with an angled surface ofthe wedge facing distally.
 14. The assembly according to claim 11,wherein a proximal end of the annular ring defines chamfers, each of thechamfers being axially aligned with one of the retention openings. 15.The assembly according to claim 1, wherein a proximal end of the annularring defines a chamfer axially aligned with the lock opening.
 16. Asurgical system comprising: a surgical instrument including a distal enddefining a lock window; a shell assembly having a proximally extendingannular ring that defines a cylindrical opening, the annular ringdefining a lock opening therethrough, the shell assembly defining afirst retention slot adjacent the annular ring on an opposite side ofthe annular ring from the lock opening, the distal end of the surgicalinstrument received within the cylindrical opening with the lock openingradially aligned with the lock window; and a locking collar positionedabout the annular ring, the locking collar having a body, a lock, and afirst retention tab, the body including the at least one releasesurface, the lock extending from an inner surface of the body spacedfrom the at least one release surface, the locking collar having alocked configuration wherein the lock extends through into the lockwindow to secure the shell assembly to the distal end of the surgicalinstrument and an unlocked configuration wherein the lock is disengagedfrom the lock window such that the shell assembly is detachable from thedistal end of the surgical instrument, the first retention tab beingreceived within the first retention slot to prevent a side of thelocking collar opposite the lock from moving outwardly in relation tothe annular ring when the at least one release surface is pressedinwardly towards the annular ring.
 17. A method of using a loading unit,the method comprising: aligning a locking collar with a shell assembly;and sliding the loading unit distally over a proximally extendingannular ring of the shell assembly, a lock of the locking collarengaging the annular ring such that the lock is moved outwardly towardsan unlocked configuration of the locking collar until the lock isaligned with a lock opening defined through the annular ring, resilienceof a body of the locking collar urging the locking collar towards alocked configuration of the locking collar to move the lock through thelock opening, a retention tab of the locking collar positioned on anopposite side of the locking collar from the lock sliding into aretention slot defined by the shell assembly to prevent the oppositeside of the locking collar from moving outwardly.
 18. The methodaccording to claim 17, further comprising attaching the loading unit toa distal end of a surgical instrument including: aligning the loadingunit with the distal end of the surgical instrument; and sliding theloading unit over the distal end of the surgical instrument such thatthe lock of the locking collar engages the distal end of the surgicalinstrument, the distal end moving the lock outwardly to urge the lockingcollar towards the unlocked configuration until the lock is aligned witha locking window defined in the distal end of the surgical instrument,the lock being urged through the locking window by resilience of thebody of the locking collar to secure the loading unit to the distal endof the surgical instrument.
 19. The method according to claim 18,further comprising actuating a shell assembly of the loading unit withthe surgical instrument after the loading unit is attached to the distalend of the surgical instrument.
 20. The method according to claim 19,further comprising detaching the loading unit from the distal end of thesurgical instrument after actuating the shell assembly including: movinga release surface of the locking collar inwardly to move the lockoutwardly such that the lock is disengaged from the locking window ofthe distal end of the surgical instrument, the retention tab of thelocking collar engaging the shell assembly to prevent the side of thelocking collar opposite the lock from moving outwardly in response tomoving the release surface of the locking collar inwardly; and slidingthe loading unit off of the distal end of the surgical instrument.